JP3837357B2

JP3837357B2 - Electronic pen data input device for computer and coordinate measuring method

Info

Publication number: JP3837357B2
Application number: JP2002109737A
Authority: JP
Inventors: 龍哲趙; 錫漢李; 慶植慮; 宰源李
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2001-04-12
Filing date: 2002-04-11
Publication date: 2006-10-25
Anticipated expiration: 2022-04-11
Also published as: KR20020080171A; US6897854B2; US20020148655A1; KR100408518B1; JP2003029915A

Description

【０００１】
【発明の属する技術分野】
本発明はコンピュータ用電子ペンデータ入力装置及びその作動方法に係り、より詳細にはコンピュータ応用機器に３軸加速度センサー及び光学式３次元測定装置を利用して電子ペンの筆記動作に関する情報を有無線で送信するコンピュータ用電子ペンデータ入力装置及び座標測定方法に関する。
【０００２】
【従来の技術】
現在、個人携帯用端末機またはコンピュータ応用機器にペンの筆記内容を入力するためにＬＣＤタブレットやデジタイザタブレットのような２次元センサー配列を含む入力装置が広く使われている。このような入力装置は比較的大面積の２次元センサー配列を必要とするために別の感知平面が必要である。したがって、携帯し難くて所定の空間を占め、またコスト面でも短所がある。技術的な趨勢から見る時、個人携帯用端末機は段々小型化して腕時計状や財布状の携帯用端末機に変化している。このような小型化の趨勢によってその表示画面も縮まるために従来のタブレットを利用した筆記方式は入力空間が縮まって自然な筆記動作によるデータ入力がさらに難しくなる。
【０００３】
前記問題点を解決するために、物理的タブレットなしに一般の平面上で単一電子ペンだけを利用して文書入力が可能であれば従来のペン入力装置に比べて広い入力空間を提供されるために自然な筆記入力が可能なので非常に効果的である。このような自己運動感知方式の電子ペンを利用した文書または絵の入力のためにはある基準座標系に対する電子ペンチップの位置座標を連続的に求められなければならない。しかし、大部分の筆記動作はペンを筆記面と接触したダウン状態で行い、移動する場合にはペンを筆記面と接触しないアップ状態となる。ペンの連続的な座標値を求めるためには接触または非接触状態でもその位置値を精密に測定できる手段を必要とする。
【０００４】
従来の電子ペン状の入力装置は大きく２つに分けられるが、ペン外部でペンチップの座標を測定する方式とペン内部でペンチップの運動を測定する方式とに分けられる。
【０００５】
ペン外部でペンチップの座標を測定する方式として、３角測量方式（米国特許第５,１６６,６６８号）、電磁波（米国特許第５,９７７,９５８号）または超音波（米国特許第４,４７８,６７４号）の飛行時間差を利用する方式などがある。しかし、前記方式はペンから発信信号を送って外部から受信する形になっているために携帯用端末機のような装置では端末機の本体に受信部を装着しなければならないので携帯が不便な短所がある。
【０００６】
また、ペン内部でペンチップの座標を測定する内蔵方式はペン内部でペンチップの運動を感知する方式であって、初期にはボールの回転を利用する方式（米国特許第５,０２７,１１５号）、ペンに作用する力を測定する方式（米国特許第５,１１１,００４号、米国特許第５,９８１,８８３号）があったが、ペンが筆記面から離れればペンの運動を測定し難い短所がある。そして、ペン内部に装着された２軸または３軸加速度センサーを利用して二重積分を通じて電子ペンの位置運動を求める方式（米国特許第５,２４７,１３７号、ＷＯ第９４／０９,４４７号、米国特許第５,５８７,５５８号）が提案された。しかし、加速度センサーをペンチップに装着し難い問題点があり、一定の高さに装着する場合にはペン中心軸の傾斜角に対する影響を考慮しないため大きな位置誤差を招く恐れがある。また、加速度信号を二重積分することによって累積誤差が増加するので正確な運動を測定し難い短所がある。
【０００７】
このようなペンの傾斜角に対する影響を補正するためにＡ.ＴＣｒｏｓｓ社（米国特許第５,４３４,３７１号）で２軸以上の加速度センサー素子をペンチップに移動させ、信号処理部はペンの上部に移動させる方法を提案しているが、センサー素子及び信号処理部が分離されていて電気的な雑音の影響が大きくて、ペン先端にインクを装着できない問題点がある。一方、Ｓｅｉｋｏ社（日本特許平６−６７,７９９号）では傾斜角補正のために２軸加速度と２ジャイロを利用して加速度は二重積分でその位置を求め、ペンの角速度を単積分してペンの傾斜角を測定する方式を提案している。また、Ｒｉｃｈｏ社（米国特許第５,９０２,９６８号、米国特許第５,９８１,８８４号）ではペン内部に３軸加速度センサーと３軸ジャイロセンサーを内蔵して一般的な３次元筆記運動をするペンチップの位置を求める方法を提示している。しかし、入力する平面が常に重力方向に垂直でなければならないために使用上の制約があり、前記慣性センサー（加速度センサー、ジャイロ）を利用する方式において加速度は二重積分、角速度は単積分を通じてペンの位置及び角度を求めるが、センサー信号の雑音やドリフトにより加速度系の場合は時間の自乗累乗、ジャイロの場合には時間に比例する形に累積誤差が増加して精密なペンチップの運動を推定し難い問題点がある。
【０００８】
前記累積誤差を減らすために最近インターセンス社では３軸加速度センサー及び３軸ジャイロを使用したペン装置に超音波センサーを追加して慣性センサー（加速度、角速度）から発生する位置累積誤差を減らす技術を提示している。しかし、このような外部センサーの追加は携帯性に悪い問題点がある。
【０００９】
【発明が解決しようとする課題】
本発明では前記従来の技術の問題点を解決するために、任意の角度で一般の平面に筆記動作をしたり、平面から離れて筆記動作をする場合にも慣性センサーの累積誤差を減らしつつ連続的な電子ペンの運動を精密に追従できるコンピュータ用電子ペンデータ入力装置及び座標測定方法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
前記目的を達成するために本発明ではペン状のハウジングを有する電子ペンにおいて、前記電子ペンの中心軸の筆記面に対する傾斜角及び前記電子ペンの筆記面に対する高さを測定するための光学式３次元測定装置と、前記電子ペンの３次元運動による移動量を測定するための３軸加速度センサーと、前記測定された傾斜角、高さ、及び、移動量に関する情報を外部演算装置に送信するための通信手段とを含むことを特徴とするコンピュータ用電子ペンデータ入力装置を提供する。
【００１１】
本発明において、前記光学式３次元測定装置は所定の筆記面にスポットを形成させるためにビームを放出する発光部と、前記筆記面に形成されたビームスポットを感知する感知部とを含み、前記発光部はビームを放出させる光源と、前記光源で生じた発散ビームを平行にする第１レンズと、前記第１レンズを通したビームを分離させる格子と、前記第１レンズを通したビームを筆記面に向けて投射させる第２レンズとを含み、前記感知部は前記筆記面に結ばれたスポットビームを１次的に集光するカメラレンズと、前記カメラレンズを通過したビームを感知する位置検出器とを含むことが望ましい。
【００１２】
本発明において、前記光学式３次元測定装置は前記感知部で受け入れたスポットビームを利用してビームスポットの位置を検出する信号処理回路と、前記検出されたビームスポットの位置を利用して前記電子ペンの前記筆記面に対する高さ及び傾斜角を演算する演算器とをさらに含むことが望ましい。
【００１３】
本発明において、前記電子ペンは前記発光部の光源のオン／オフを調節する制御器及び、前記外部演算装置で演算された前記情報を貯蔵するための貯蔵手段をさらに含むことが望ましい。
【００１４】
本発明において、前記通信手段はＲＦ通信装置であることが望ましい。
【００１５】
前記電子ペンは前記３軸加速度センサー及び前記光学式３次元測定装置で測定されたデータを利用して電子ペンチップの位置を演算するための中央処理装置をさらに含み、前記電子ペンの筆記面に対する接触有無を検出するための前記電子ペンチップと連結された応力センサーをさらに含むことが望ましい。
【００１６】
本発明において、前記電子ペンが筆記面に接触されて筆記をする場合、インクを噴射するために前記電子ペンチップと連結されたインク収容部をさらに含むことが望ましい。
【００１７】
また、本発明では、ペン状のハウジングを有する電子ペンと、前記電子ペンの中心軸の筆記面に対する傾斜角及び前記電子ペンの筆記面に対する高さを測定するための光学式３次元測定装置と、前記電子ペンの３次元運動による移動量を測定するための３軸加速度センサーと、前記３軸加速度センサー及び前記光学式３次元測定装置で測定されたデータを利用して前記電子ペンチップの位置座標を演算するための中央処理装置と、前記演算された電子ペンチップの位置座標を外部コンピュータまたは個人携帯用端末機に送信するための通信手段とを含むコンピュータ用電子ペンデータ入力装置の座標測定方法において、（Ａ）前記光学式３次元測定装置によって前記電子ペンと筆記面とがなす傾斜角及び筆記面に対する高さを測定し、前記３軸加速度センサーによって前記電子ペンの３次元運動情報を測定する段階と、（Ｂ）前記測定された筆記面に対する電子ペンの傾斜角、高さ、及び、３次元運動情報をコンピュータまたは携帯用端末機の中央処理装置で変換して電子ペンチップの座標を抽出する段階と、（Ｃ）前記抽出された電子ペンチップの座標を前記通信手段を利用して外部コンピュータまたは携帯用端末機に送信する段階とを含むことを特徴とするコンピュータ用電子ペンデータ入力装置の座標測定方法を提供する。
【００１８】
本発明において、前記光学式３次元測定装置は筆記面にスポットを形成させるためのビームを放出する発光部と、前記筆記面に形成されたビームスポットを感知する感知部とを含み、コンピュータ用電子ペンデータ入力装置の座標測定方法において、前記（Ａ）段階の電子ペンと筆記面とがなす傾斜角及び筆記面に対する高さを測定する段階は前記発光部からビームを放出する段階と、前記放出されたビームを筆記面に投射して５つ以上のビームスポットを形成させる段階と、前記ビームスポットの反射ビームを集光する段階と、前記集光されたビームを利用して電子ペンの筆記面となす傾斜角及び高さに関する情報を位置検出器を通じて検出する段階とを含むことが望ましい。
【００１９】
本発明において、前記傾斜角及び高さを検出する段階は、前記集光された５つ以上のビームスポットの情報を利用して楕円方程式により前記電子ペンの傾斜角及び筆記面に対する高さを求める段階と、前記求められた傾斜角及び高さの各々を微分して傾斜角速度及び垂直速度を初期値から求める段階とを含むことが望ましい。
【００２０】
本発明において、前記（Ｂ）段階は加速度信号から重力成分を除去する段階と、前記重力成分が除去された加速度信号を第１次積分して電子ペンの移動速度を求める段階と、前記電子ペンチップの速度を求めた後、筆記面に対する垂直速度を利用して累積誤差を補正する段階と、運動累積誤差補正された前記電子ペンの移動速度を第２次積分して前記電子ペンの変位移動量を求める段階と、前記電子ペンの変位移動量の累積誤差を補正して電子ペンチップの座標を求める段階とを含むことが望ましい。
【００２１】
本発明において、前記（Ｂ）段階は前記３軸加速度センサーから出る加速度信号に対してローパスフィルタリングを行う段階をさらに含み、前記（Ｃ）段階の通信手段はＲＦ通信方法によるものであることが望ましい。
【００２２】
また、本発明では、ペン状のハウジングを有する電子ペンと、前記電子ペンの中心軸の筆記面に対する傾斜角及び前記電子ペンチップの筆記面に対する高さを測定するための光学式３次元測定装置と、前記電子ペンの３次元運動による移動量を測定するための３軸加速度センサーと、前記測定された傾斜角、高さ、及び、移動量に関する情報をコンピュータまたは携帯用端末機に伝送するための通信手段とを含むコンピュータ用電子ペンデータ入力装置の作動方法において、（Ａ）前記光学式３次元測定装置によって前記電子ペンと筆記面とがなす傾斜角及び筆記面に対する高さを測定し、前記３軸加速度センサーによって前記電子ペンの３次元運動情報を測定する段階と、（Ｂ）前記測定された傾斜角、高さ、及び、３次元運動情報に関する情報を前記通信手段を利用してコンピュータまたは携帯用端末機に送信する段階と、（Ｃ）前記測定された筆記面に対する電子ペンの傾斜角、高さ、及び、３次元運動情報をコンピュータまたは携帯用端末機の中央処理装置で変換して電子ペンチップの座標を抽出する段階とを含むことを特徴とするコンピュータ用電子ペンデータ入力装置の座標測定方法を提供する。
【００２３】
本発明において、前記光学式３次元測定装置は筆記面にスポットを形成させるためにビームを放出する発光部と、前記筆記面に形成されたビームスポットを感知する感知部とを含み、前記（Ａ）段階の電子ペンと筆記面とがなす傾斜角及び筆記面に対する高さを測定する段階は、前記放出されたビームを筆記面に投射してビームスポットを形成させる段階と、前記ビームスポットの反射ビームを集光する段階と、前記集光されたビームを位置検出器を通じて検出する段階とを含むことが望ましい。
【００２４】
本発明において、前記（Ｃ）段階は加速度信号から重力成分を除去する段階と、前記重力成分が除去された加速度信号を第１次積分して電子ペンの移動速度を求める段階と、前記電子ペンチップの速度を求めた後、筆記面に対する垂直速度を利用して累積誤差を補正する段階と、運動累積誤差補正された前記電子ペンの移動速度を第２次積分して前記電子ペンの変位移動量を求める段階と、前記電子ペンの変位移動量の累積誤差を筆記面に対する高さを利用して補正して電子ペンチップの座標を求める段階とを含むことが望ましい。
【００２５】
本発明において、前記通信手段はＲＦ通信方法によるものであることが望ましい。
【００２６】
【発明の実施の形態】
以下、図面を参考して本発明についてより詳細に説明する。図１は本発明による電子ペンの構造を示した概略図である。図１に示したように、本発明による電子ペンはペンの３次元運動による移動量を測定するための３軸加速度センサー４及びペンの傾斜角と高さを測定するための光学式３次元測定装置６−Ａを具備したことを特徴とする。また、前記３軸加速度センサー４で加速度信号を受け入れる中央処理装置（ＣＰＵ）５が設けられ、このような加速度信号を積分して速度を求められ、また２次積分により位置移動量を求められる。光学式３次元測定装置６−Ａはビームを生じる発光部７及びこれを感知するための受光部８よりなっており、本発明では発光部７で５点以上のビームスポット１３を得るためにビームを筆記面１２に投射して電子ペンの傾斜角と高さに関する情報を得ることを特徴とする。すなわち、図１に示したように原形リング状にスポット１３を得るためにビームを筆記面１２に投射すれば、筆記面１２に対するペンの角度及び高さによって結ばれる楕円形の形態及び大きさが変わるのでこのスポット１３の座標値を測定してペンの傾斜角及び高さを測定する。前述されたようなペンの傾斜角、高さ及び移動量に関する情報を受け入れて処理するための光学信号処理装置６及びＣＰＵ５を具備することが望ましい。しかし、本発明による電子ペンはその内部にＣＰＵ５を含むが、前記３軸加速度センサー４及び光学式３次元測定装置６−Ａにより得られた情報をコンピュータまたは個人携帯用端末機で処理する場合には前記ＣＰＵ５は不要となる。すなわち、前記中央処理装置は選択的である。
【００２７】
そして、電子ペンを一定時間以上容易に使用するためのバッテリー３を含み、前記のようなペンの運動に関する情報を貯蔵するための貯蔵装置２を含むことが望ましい。また、前記電子ペンに関する情報をコンピュータまたは個人携帯用端末機に伝送するための送信装置１が必要であるが、本発明による電子ペンはそのデータ送信において有線または無線いずれも可能であることを特徴とし、無線の場合ＲＦ通信装置を含むことが望ましい。通常的にペンによる筆記動作はペン−ダウン、ペン−アップの連続動作で構成されるのでこのような動作情報を得るために筆記面１２に対する接触有無を判別するための応力センサー９を含みうる。また、紙等に直接記録する必要があるのでこのためにペン内部にインク収容部１０をさらに含みうる。
【００２８】
図２は、本発明による電子ペンの光学式３次元測定装置６−Ａの一実施形態を示した図面である。前述されたように光学式３次元測定装置６−Ａは電子ペンの筆記面１２に対する高さ及び傾斜角を測定するためのものであって多様な構造を有することができ、ここで一例を調べれば次の通りである。図２に示した実施形態はペンの中心軸と３次元測定装置６−Ａで投射及び入射する光経路と偏差を有する構造を示す。
【００２９】
まずその構造を調べれば、ビームを放出する光源２１と広がるビームを平行にする第１レンズ２２、一定の構造を有する格子２３、前記光源２１から放出されたビーム２５を筆記面１２に向けて再度平行に投射する第２レンズ２４、筆記面１２で散乱されたビーム２６の一部を集光するカメラレンズ２７、前記カメラレンズ２７で集光されたビームを受け入れる位置検出器２８、前記位置検出器２８の信号を利用して位置を感知する信号処理部と筆記面１２に対する高さと傾斜角を演算する演算器とより構成されている。
【００３０】
このような光学式３次元測定装置６−Ａでのビームの放出から情報の出力までの原理についてより詳細に説明すれば次の通りである。まず光源２１からビーム２５、例えば可視光線または赤外線を放出する。この場合、前記光源２１はレーザーダイオード、ＬＥＤ（ｌｉｇｈｔｅｍｉｔｔｉｎｇｄｉｏｄｅ）など通常的な光源として使われるものであれば制限がない。前記光源２１から放出されたビームは、例えば、第１レンズ２２により平行した円筒形のビームになり、格子２３の構造により一定の半径を有する円周上に５つ以上のビームに分離される。前記格子２３から分離されたビームは精密な平行ビームのために第２レンズ２４を経て筆記面１２方向に投射される。筆記面１２に投射されたビームはその投射角による扇状楕円形でスポット１３を形成する。ここで、前記筆記面１２が木または紙のように散乱面である場合にはビームが多様な角度で広がり、一部がカメラレンズ２７に集光され、位置検出器２８により受入れられる。このように得られたビームに関する情報、すなわち、ビームスポット１３の位置は信号処理部で求められ、演算器を経て５点の各々の座標から電子ペン筆記面１２に対する高さと傾斜角を出力する。これら位置検出器２８、信号処理部をいずれも一体型にした位置検出器で構成できる。ここで、前記光源２１での電力消費を減らすために作動をしない場合に電力を遮断できるように制御器にオン／オフを制御する機能を有するように構成することが望ましい。
【００３１】
図３は、本発明による電子ペンの光学式３次元測定装置の他の実施形態を示した図面である。図３に示した光学式３次元測定装置は、ハーフミラー２９を用いて前記図２とは異なって筆記面に対するビームの中心軸を電子ペンの中心軸と一致させたことを特徴とし、したがってビームスポットの走査及び反射軸を電子ペンの中心軸と同一に構成したものである。
【００３２】
図４Ａないし図４Ｆは、本発明による電子ペンの光学式３次元測定装置において、電子ペンの傾斜角及び軸方向の変化によりビームスポットの形態が変わる原理を示した図面である。ここで、ビームが投射される面をＸ−Ｙ軸に示し、前記投射面に垂直の軸をＺに定義する。３方向の各々の傾斜角変数θ１、θ２、θ３の変化によって筆記面に結ばれたビームのパターンが変化する。θ１は筆記面１２に対する法線方向の軸Ｚｓと電子ペンの中心軸間の角度を意味し、θ２は筆記面Ｘｓ−Ｙｓと電子ペンの中心軸が筆記面に投影される時の回転した角度を意味し、θ３は電子ペンの中心軸自体に対する回転角を意味する。また、δＺａは電子ペンチップと筆記面との距離を示す。ここで、このようなビームのパターンは楕円形であり、筆記面１２に対する傾斜角が変化するにつれて楕円の長軸、短軸及びその楕円の傾斜角が変化する。また、筆記面に対する高さ方向のペン運動により楕円の大きさが変わるが、電子ペンが筆記面に近くなれば楕円全体の大きさが拡大され、遠ざかれば縮少される傾向を示す。したがって、筆記面でのビームパターンを読込んで解析すれば電子ペンの筆記面に対する傾斜角及び高さを求められる。
【００３３】
図４Ｂは、θ１の変化による楕円の長軸及び短縮の変化を示したものであって、各々左側形態からθ１が０より小さい場合、同じ場合及び大きい場合を示している。図４Ｃは、θ２の変化による楕円の長軸、短軸及び傾斜角変化を示した図面であって、前記図４Ｂと同じくθ２が０より小さい場合、同じ場合及び大きい場合を示している。図４Ｄは、θ３の変化による円周上にあるスポットの変化を示したものであって、ここでθ３は電子ペンの中心軸の回転角を示すためθ３の変化によって５つのスポットの位置が変わることを簡略に示した。このようにスポットの位置は変化するが、楕円の形状は変化しない。しかし位置検出器２８で測定された楕円映像は映像面がθ３だけ回転した形に現れるのでその回転角度を測定できる。図４ＥはδＺａの変化による図面形態を示したものであって、これは前述されたように電子ペンが筆記面に近くなれば楕円全体が拡大され、遠ざかれば縮少される傾向を示す。
【００３４】
図４Ｆは、位置検出器映像面Ｑと筆記面に結ばれたスポットとの幾何学的関係を示したものである。ここで、座標Ｘｃ、Ｙｃ、Ｚｃはカメラレンズの座標系である。位置検出器の焦点をｆｃ、ビームの半径をｒ、位置検出器のレンズ軸と光源の軸がなす間角をΦと定義する。すると、光学式３次元測定装置で測定する変数はビーム軸に対する筆記面の傾斜角θ１、θ２と回転角θ３、カメラレンズ座標系で筆記面に結ばれたビーム中心座標Ｐｘ、Ｐｚである。
【００３５】
映像面Ｑに結ばれる５つ以上のビームスポットがなす楕円の方程式で定義すれば、楕円方程式は次のように表現できる。
【数１】

ω₁、ω₂、ω₃、ω₄、ω₅はレンズの焦点距離ｆｃ、投射されるビームの半径ｒ、カメラレンズ軸と光源軸がなす間角Φ、筆記面に対する電子ペンの垂直距離Ｐｚ及び電子ペンの傾斜角θ１、θ２の関数よりなる。前記数式１でのＸ−Ｙ平面の楕円方程式で未知数が５つであるため最小限５点に対する映像点の座標が必要である。したがって本発明による電子ペンの光学式３次元測定装置では光源から放出されたビームを映像面で５つ以上のスポットが形成されるように構成することが望ましい。これを下記数式２を参考してより詳細に説明する。
【数２】

【００３６】
５つのスポットの座標を利用して前記映像面の楕円方程式が計算されればω₁、ω₂、ω₃、ω₄、ω₅を求められ、ここでレンズの焦点距離ｆｃ、投射されるビームの半径ｒ、カメラレンズ軸と光源がなす間角Φは本発明による電子ペンの製作時に分かるので、ビーム軸に対する筆記面の傾斜角θ１、θ２をω₁、ω₂から一次的に唯一に計算でき、ω₃、ω₄、ω₅からＰｘ、Ｐｚを決定できる。一方、ビームの回転角θ３は図４Ｄに提示された方法のように映像でスポットが回転した角度を計算して求められる。この時、映像面にある楕円方程式を円の方程式に変換した後、回転角θ３を決定することが望ましい。これは前記数式２を通じてビーム軸とカメラ軸との幾何学的変換関係を全部計算したので、カメラレンズ中心軸の移動と回転を通じて光源のビーム軸と一致させればカメラ映像面に結ばれる仮想の円に対する映像を計算でき、円の中心でスポットが回転した角度を計算して回転角θ３を決定する。
【００３７】
このような楕円方程式の媒介変数と筆記面との関係は公知の参考文献（Ｄ.Ｗｅｉ,“Ｔｈｅｕｓｅｏｆｔａｐｅｒｌｉｇｈｔｆｏｒｏｂｊｅｃｔｒｅｃｏｇｎｉｔｉｏｎｓ”：Ｒｏｂｏｔｖｉｓｉｏｎ，ＩＦＳＬｔｄ．ｐ１４３〜１５３及び“平面物体認識のための円筒形レーザービーム投射型視覚情報処理システムの開発”：金ゾンヒョング、韓国科学技術院機械工学科修士論文，１９８９）にその類似技術が紹介されている。
【００３８】
図５は、本発明で使われる３軸加速度センサー４、光学式３次元測定装置６−Ａ及び電子ペンチップ１１での各座標系を示した図面である。まず電子ペンチップの座標系をＯｓ、３軸加速度センサー４の座標系をＯａ、そして光学式３次元測定装置６−Ａの座標系をＯｃと定義する。電子ペンの構造上前記３つの座標系は差があるので、光学式３次元測定装置６−Ａで求められた電子ペンの傾斜角及び高さ情報は電子ペンチップ１１で求められた傾斜角及び高さ情報と差がある。特に、図２の光学式３次元測定装置６−Ａの実施形態においては傾斜角も差がある。これに対する補正をするために図５に示されたようにベクトルＥを事前に計算しておくことが望ましい。また、Ｏｃ座標系で求めた傾斜角と傾斜角速度と３軸加速度センサー４のＯａ座標系で求めた情報の差はベクトルＤを求めればそれら間の幾何学的変換関係を求められる。３軸加速度センサー４の座標系Ｏａで求めた速度及び位置移動量は結局電子ペンチップの座標系Ｏｓに変換し、この場合、Ｏａ−Ｏｓ間の変換関係はベクトルＬで示すことができ、これは本発明による電子ペンの設計過程で決定できる変数である。
【００３９】
図６は、本発明による電子ペンの運動を描写するのに必要な電子ペンの筆記面に対する傾斜角と高さ測定変数、３軸加速度センサー４座標系Ｏａでの速度、角速度、電子ペンチップ１１のＯｓ座標系でのペンチップの速度及び筆記面の法線ベクトルｎを示したものである。
【００４０】
図７は、本発明による電子ペンの情報処理過程であるセンサーフュージョンのための知覚ネットの基本構造を示したものである。まず、３軸加速度センサー４から出る信号を利用してＦＴＭ１（ｆｅａｔｕｒｅｔｒａｎｓｆｏｒｍａｔｉｏｎｍｏｄｕｌｅ）により電子ペンの速度及び位置を求め、次に光学式３次元測定装置６−Ａから出る信号を利用してＦＴＭ２で電子ペンの筆記面１２に対する傾斜角、速度及び高さを求める。次の段階でＣＳＭ１（ｃｏｎｓｔｒａｉｎｔｓａｔｉｆａｃｔｉｏｎｍｏｄｕｌｅ）とＣＳＭ２で３軸加速度センサー４及び光学式３次元測定装置６−Ａから受け入れた情報を下記数式２で与えられた数学的制限条件式を利用して相互融合させ、これによって誤差が減少したデータがＦＴＭ１にフィードバックされつつ新しい速度及び加速度信号を得られるようになる。数式２は各々ＣＳＭ１（位置）、ＣＳＭ２（速度）に対する制限条件式を示している。前記のセンサー融合技法の基本原理は公知の参考文献（ＳｕｋｈａｎＬｅｅ、“Ｓｅｎｓｏｒｆｕｓｉｏｎａｎｄｐｌａｎｎｉｎｇｗｉｔｈｐｒｅｃｅｐｔｉｏｎ−ａｃｔｉｏｎｎｅｔｗｏｒｋ”，１９９６，ＩｎｔｅｒｎａｔｉｏｎａｌｃｏｎｆｅｒｅｎｃｅｏｎＭｕｌｔｉｓｅｎｓｏｒＦｕｓｉｏｎａｎｄＩｎｔｅｇｒａｔｉｏｎｆｏｒＩｎｔｅｌｌｉｇｅｎｔＳｙｓｔｅｍｓ）に紹介されている。
【数３】

ここで、ＣＳＭ１の制限条件式（１）は電子ペン内部で求めた位置成分Ｘａ、Ｙａ、Ｚａを電子ペンチップ１１の座標系Ｘｓ、Ｙｓ、Ｚｓに変換する時に筆記面の高さδＺｓに対する制限条件式を示したものである。位置Ｘｓ、Ｙｓ、Ｚｓは電子ペン内部での加速度信号を積分して速度を求めた後、これを再び積分して位置を示したものである。ここでα、β、γ、λは電子ペンの先端までの長さ及び電子ペンの筆記面に対する傾斜角により各々求められる定数である。ここで、前記制限条件式による電子ペン内部での位置移動量は各々電子ペンチップ１１の高さに影響を及ぼしうるため、各信号の成分誤差の線形組合わせにより電子ペンチップ１１の高さδＺｓを満足する形で示すことによって、各センサーの位置信号Ｘｓ、Ｙｓ、Ｚｓに累積された誤差を減少させうる。
【００４１】
一方、ＣＳＭ２は電子ペン内部での加速度信号を単積分して求めた速度成分Ｖａ、電子ペンの角速度Ω、電子ペンの先端までの長さＬをベクトルで示したものであって、電子ペンチップ１１での垂直速度Ｖｓ／ｎはペンチップでの線速度Ｖｓと平面の法線ベクトルｎにより計算される。これは電子ペンの内部で求めた速度成分Ｖａｘ、Ｖａｙ、Ｖａｚが筆記面に対する制限条件式を満足な形であって、電子ペンが筆記面に接触している状態ではＶｓ／ｎ＝０の関係になることを意味する。また、電子ペンが筆記面と接触されていない状態でも各速度成分の線形組合わせが制限条件式を満足せねばならないために速度に対する累積誤差を減らせる。前記のような構造の本発明によるフィードバックシステムのセンサーフュージョンを通じて累積誤差の増加を防止し、情報量を一定の誤差範囲内に維持させうる。
【００４２】
図８は、本発明による電子ペンの３軸加速度センサー４及び光学式３次元測定装置６−Ａにおけるデータ処理に関するフローチャートである。まず光学式３次元測定装置６−Ａで、筆記面１２で散乱されたビームから求めた５つのビームスポット１３の楕円情報を利用すれば位置検出器２８で電子ペンの筆記面１２に対する高さ及び傾斜角を求める。このようなデータを求める過程は前記図４に説明されたように５つ以上のビームスポット１３の座標を利用して楕円方程式を求めて計算される。各傾斜角と高さに対する情報を求めれば、これに対する微分値である傾斜角速度及び垂直速度を初期値から求められる。
【００４３】
そして、３軸加速度センサー４で電子ペンの加速度に関する情報信号を読込み、この時、３軸加速度センサー４から出る情報信号は雑音が多いのでローパスフィルタリングを行う。一般に加速度信号には静的な重力成分が常に含まれているために、純粋な筆記動作による運動信号を抽出するためには加速度信号で重力成分を除去しなければならない。重力に対する各信号の大きさは計算だけでは求め難いため、あらかじめ初期に静止状態で求めた重力値を利用して電子ペンの傾斜角の変化によって変わる加速度値で前記重力成分を除去しなければならない。それで、純粋な電子ペン運動による加速度信号が求められる。次に、このような加速度信号は１次積分を通じて電子ペンの移動速度に関する情報を求められるようになる。しかし情報信号の雑音によって積分に対する累積誤差が生じるので、これを補正するために電子ペンの先端で求められる速度を利用して速度に対する制限条件式である前記数式３の（２）を適用させる。電子ペンチップ１１での速度を求めるためには電子ペンの回転角速度及び電子ペンの幾何変数についての考慮が必要である。それで速度信号で雑音が減った修正速度値が求められるが、これは前記図７に示されたように連続的に新しい速度値に更新する。
【００４４】
次に、前記１次積分させた移動速度で２次積分を行って電子ペンの変位移動量を求める。これに対する累積位置誤差は前記数式３の（１）を利用して計算し、前記図７に示したように新しく修正された位置信号を求める。前記段階を経て加速度信号で二重積分により生じうる累積誤差を段階的に前記数式２の制限条件式の各々を利用して補正することによって、最終的に電子ペンの移動量Ｘｓ、Ｙｓ、Ｚｓを求められる。このような電子ペンの移動量データを利用して本発明による電子ペンの位置データを求めうる。
【００４５】
図８は、３軸加速度センサー４及び光学式３次元測定装置６−Ａから電子ペンの傾斜角、傾斜角速度、高さ及び垂直速度を中央処理装置５により計算する実施形態を示すものである。前述したように、このようなデータ処理は本発明による電子ペン内部に３軸加速度センサー４、光学式３次元測定装置６−Ａ及び中央処理装置５を具備した状態で計算して結果値をコンピュータまたは個人携帯電話端末機に有無線で送信でき、単に測定分だけを送信してコンピュータや個人携帯用端末機の中央処理装置などで計算することもできる。
【００４６】
【発明の効果】
本発明によれば、コンピュータまたは個人携帯用端末機に筆記面と接触した状態及び非接続した状態での有無線電子ペンの動作による記録情報の、重力加速度及び情報信号の雑音による加速度の積分による累積誤差を最小化することによって電子ペンチップの純粋な位置座標を容易に求められる長所がある。
【図面の簡単な説明】
【図１】本発明によるコンピュータ用電子ペンデータ入力装置に関する概略図である。
【図２】本発明による電子ペンの光学式３次元測定装置の一実施形態を示した図面である。
【図３】本発明による電子ペンの光学式３次元測定装置の他の実施形態を示した図面である。
【図４Ａ】本発明による電子ペンの光学式３次元測定装置において、電子ペンの傾斜角及び軸方向の変化によるビームスポットの形態が変わる原理を示した図面である。
【図４Ｂ】図４Ａと同様の図である。
【図４Ｃ】図４Ａと同様の図である。
【図４Ｄ】図４Ａと同様の図である。
【図４Ｅ】図４Ａと同様の図である。
【図４Ｆ】図４Ａと同様の図である。
【図５】本発明で使われる３軸加速度センサー、光学式３次元測定装置及び電子ペンチップでの各座標系を示した図である。
【図６】本発明による電子ペンの運動を描写するのに必要な電子ペンの筆記面に対する傾斜角と高さ測定変数、３軸加速度センサー座標系Ｏａでの速度、角速度、電子ペンチップのＯｓ座標系でのペンチップの速度及び筆記面の法線ベクトルｎを示した図である。
【図７】本発明による電子ペンの情報処理過程であるセンサーフュージョンのための知覚ネットの基本構造を示した図である。
【図８】本発明による電子ペンの３軸加速度センサー及び光学式３次元測定装置におけるデータ処理に関するフローチャートを示した図である。
【符号の説明】
１送信装置
２貯蔵装置
３バッテリー
４３軸加速度センサー
５中央処理装置
６光学信号処理装置
６−Ａ光学式３次元測定装置
７発光部
８受光部
９応力センサー
１０インク収容部
１１電子ペンチップ
１２筆記面
１３ビームスポット
２１光源
２２第１レンズ
２３格子
２４第２レンズ
２５放出ビーム
２６スポット反射光
２７カメラレンズ
２８位置検出器
２９ハーフミラー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic pen data input device for a computer and a method of operating the same, and more particularly, information relating to a writing operation of an electronic pen using a three-axis acceleration sensor and an optical three-dimensional measuring device in a computer application device. The present invention relates to an electronic pen data input device for a computer and a coordinate measuring method.
[0002]
[Prior art]
Currently, an input device including a two-dimensional sensor array, such as an LCD tablet or a digitizer tablet, is widely used to input pen writing contents into a personal portable terminal or a computer application device. Since such an input device requires a two-dimensional sensor array having a relatively large area, a separate sensing plane is required. Therefore, it is difficult to carry, occupies a predetermined space, and has a disadvantage in terms of cost. From the technical trend, personal portable terminals are gradually becoming smaller and changing to wristwatch-like or wallet-like portable terminals. Due to the trend toward miniaturization, the display screen also shrinks, so that the writing method using a conventional tablet is made difficult to input data by a natural writing operation because the input space is reduced.
[0003]
In order to solve the above problems, if a document can be input using only a single electronic pen on a general plane without a physical tablet, a wider input space than a conventional pen input device can be provided. Therefore, since natural writing input is possible, it is very effective. In order to input a document or picture using such a self-motion sensing type electronic pen, the position coordinate of the electronic pen tip with respect to a certain reference coordinate system must be continuously obtained. However, most writing operations are performed in a down state in which the pen is in contact with the writing surface, and when moving, the pen is in an up state in which the pen is not in contact with the writing surface. In order to obtain the continuous coordinate value of the pen, a means capable of accurately measuring the position value even in a contact or non-contact state is required.
[0004]
Conventional electronic pen-like input devices are roughly divided into two types: a method of measuring the coordinates of the pen tip outside the pen and a method of measuring the movement of the pen tip inside the pen.
[0005]
As a method of measuring the coordinates of the pen tip outside the pen, a triangulation method (US Pat. No. 5,166,668), an electromagnetic wave (US Pat. No. 5,977,958) or an ultrasonic wave (US Pat. No. 4,478). No. 674), which uses the time difference of flight. However, since the system is configured to send a transmission signal from a pen and receive it from the outside, in a device such as a portable terminal, it is necessary to attach a receiver to the main body of the terminal, which is inconvenient to carry. There are disadvantages.
[0006]
Further, the built-in method for measuring the coordinates of the pen tip inside the pen is a method for sensing the movement of the pen tip inside the pen, and initially uses a ball rotation (US Pat. No. 5,027,115), There was a method to measure the force acting on the pen (US Pat. No. 5,111,004, US Pat. No. 5,981,883), but it is difficult to measure the movement of the pen if the pen moves away from the writing surface There is. A method for obtaining the position movement of the electronic pen through double integration using a biaxial or triaxial acceleration sensor mounted inside the pen (US Pat. No. 5,247,137, WO 94 / 09,447). U.S. Pat. No. 5,587,558) has been proposed. However, there is a problem that it is difficult to mount the acceleration sensor on the pen tip. When the acceleration sensor is mounted at a certain height, an influence on the tilt angle of the pen center axis is not taken into consideration, and there is a possibility that a large position error is caused. In addition, since the accumulated error increases due to double integration of the acceleration signal, there is a disadvantage that it is difficult to measure accurate motion.
[0007]
In order to correct such an influence on the tilt angle of the pen, AT Cross (US Pat. No. 5,434,371) moves two or more axes of acceleration sensor elements to the pen tip, and the signal processing unit Although a method of moving to the upper side has been proposed, there is a problem in that the sensor element and the signal processing unit are separated and the influence of electrical noise is great, and ink cannot be attached to the tip of the pen. On the other hand, Seiko (Japanese Patent No. 6-67,799) uses a biaxial acceleration and a two gyro to correct the tilt angle, finds the position of the acceleration by double integration, and simply integrates the angular velocity of the pen. To measure the tilt angle of the pen. In addition, Richo (US Pat. No. 5,902,968, US Pat. No. 5,981,884) incorporates a three-axis acceleration sensor and a three-axis gyro sensor inside the pen for general three-dimensional writing motion. A method for finding the position of a pen tip is presented. However, since the input plane must always be perpendicular to the direction of gravity, there are restrictions in use, and in the method using the inertial sensor (acceleration sensor, gyro), acceleration is penalized through double integration and angular velocity is penetrated through single integration. The position and angle of the sensor are estimated, but due to the noise and drift of the sensor signal, the accumulative error increases in proportion to the square of the time in the case of the acceleration system and in the case of the gyro, and the movement of the pen tip is estimated accurately. There are difficult problems.
[0008]
In order to reduce the accumulated error, Intersense recently added a technology to reduce the accumulated position error generated from inertial sensors (acceleration, angular velocity) by adding an ultrasonic sensor to a pen device using a 3-axis acceleration sensor and a 3-axis gyroscope. Presenting. However, adding such an external sensor has a problem of poor portability.
[0009]
[Problems to be solved by the invention]
In the present invention, in order to solve the problems of the conventional technology, even when writing is performed on a general plane at an arbitrary angle, or when writing is performed away from the plane, the cumulative error of the inertial sensor is continuously reduced. An object of the present invention is to provide an electronic pen data input device for computers and a coordinate measuring method capable of accurately following the movement of a typical electronic pen.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in an electronic pen having a pen-shaped housing, an optical type 3 for measuring the inclination angle of the central axis of the electronic pen with respect to the writing surface and the height of the electronic pen with respect to the writing surface. A dimension measuring device, a three-axis acceleration sensor for measuring the amount of movement of the electronic pen by three-dimensional movement, and information about the measured inclination angle, height, and amount of movement are transmitted to an external computing device. And an electronic pen data input device for a computer.
[0011]
In the present invention, the optical three-dimensional measuring apparatus includes a light emitting unit that emits a beam to form a spot on a predetermined writing surface, and a sensing unit that detects the beam spot formed on the writing surface, The light emitting unit writes a light source that emits a beam, a first lens that collimates a divergent beam generated by the light source, a grating that separates the beam that passes through the first lens, and a beam that passes through the first lens. A second lens that projects toward a surface, and the sensing unit primarily collects a spot beam connected to the writing surface, and a position detection that senses the beam that has passed through the camera lens. It is desirable to include a container.
[0012]
In the present invention, the optical three-dimensional measuring apparatus uses a spot beam received by the sensing unit to detect a beam spot position, and uses the detected beam spot position to detect the electron beam. It is desirable to further include a calculator for calculating the height and the inclination angle of the pen with respect to the writing surface.
[0013]
In the present invention, it is preferable that the electronic pen further includes a controller for adjusting on / off of the light source of the light emitting unit, and a storage unit for storing the information calculated by the external arithmetic device.
[0014]
In the present invention, the communication means is preferably an RF communication device.
[0015]
The electronic pen further includes a central processing unit for calculating the position of the electronic pen tip using data measured by the three-axis acceleration sensor and the optical three-dimensional measuring device, and the electronic pen is in contact with the writing surface of the electronic pen. It is preferable to further include a stress sensor connected to the electronic pen tip for detecting presence or absence.
[0016]
In the present invention, it is preferable that the electronic pen further includes an ink storage unit connected to the electronic pen chip for ejecting ink when the electronic pen is in contact with the writing surface for writing.
[0017]
According to the present invention, an electronic pen having a pen-shaped housing, an optical three-dimensional measuring device for measuring an inclination angle of the central axis of the electronic pen with respect to the writing surface and a height of the electronic pen with respect to the writing surface; , A three-axis acceleration sensor for measuring the amount of movement of the electronic pen by three-dimensional movement, and position coordinates of the electronic pen tip using data measured by the three-axis acceleration sensor and the optical three-dimensional measuring device In a coordinate measuring method for an electronic pen data input device for a computer, comprising: a central processing unit for calculating the position of the electronic pen tip; and a communication means for transmitting the calculated position coordinates of the electronic pen tip to an external computer or a personal portable terminal. (A) The optical three-dimensional measuring device measures the tilt angle between the electronic pen and the writing surface and the height relative to the writing surface, A step of measuring three-dimensional movement information of the electronic pen by an acceleration sensor; and (B) an inclination angle of the electronic pen with respect to the measured writing surface, a height, and three-dimensional movement information of a computer or a portable terminal. Converting at the central processing unit to extract the coordinates of the electronic pen tip; and (C) transmitting the extracted coordinates of the electronic pen tip to an external computer or a portable terminal using the communication means. A coordinate measuring method for an electronic pen data input device for a computer is provided.
[0018]
In the present invention, the optical three-dimensional measuring apparatus includes a light emitting unit that emits a beam for forming a spot on a writing surface, and a sensing unit that detects the beam spot formed on the writing surface. In the coordinate measuring method of the pen data input device, the step (A) of measuring the tilt angle between the electronic pen and the writing surface and the height with respect to the writing surface are the step of emitting a beam from the light emitting unit, and the emission. Projecting the projected beam onto the writing surface to form five or more beam spots, condensing the reflected beam of the beam spot, and writing surface of the electronic pen using the collected beam And detecting information about the tilt angle and height through a position detector.
[0019]
In the present invention, in the step of detecting the tilt angle and height, the tilt angle of the electronic pen and the height relative to the writing surface are obtained by an elliptic equation using information of the five or more focused beam spots. Preferably, the method includes a step of differentiating each of the obtained inclination angle and height to obtain an inclination angular velocity and a vertical velocity from initial values.
[0020]
In the present invention, the step (B) includes a step of removing a gravitational component from the acceleration signal, a step of obtaining a moving speed of the electronic pen by first integrating the acceleration signal from which the gravitational component has been removed, and the electronic pen tip. After calculating the speed of the electronic pen, a step of correcting the accumulated error using the vertical speed with respect to the writing surface, a second-order integration of the movement speed of the electronic pen corrected for the movement accumulated error, and a displacement movement amount of the electronic pen Preferably, the method includes a step of determining the coordinate of the electronic pen tip by correcting the accumulated error of the displacement movement amount of the electronic pen.
[0021]
In the present invention, the step (B) further includes a step of low-pass filtering the acceleration signal output from the triaxial acceleration sensor, and the communication means in the step (C) is preferably based on an RF communication method. .
[0022]
In the present invention, an electronic pen having a pen-shaped housing, an optical three-dimensional measuring device for measuring an inclination angle of the central axis of the electronic pen with respect to the writing surface and a height of the electronic pen tip with respect to the writing surface; , A three-axis acceleration sensor for measuring the amount of movement of the electronic pen by three-dimensional movement, and information for transmitting the measured tilt angle, height, and amount of movement to a computer or portable terminal In the operation method of the electronic pen data input device for a computer including the communication means, (A) the inclination angle formed by the electronic pen and the writing surface and the height with respect to the writing surface are measured by the optical three-dimensional measuring device, Measuring three-dimensional motion information of the electronic pen with a three-axis acceleration sensor; and (B) regarding the measured tilt angle, height, and three-dimensional motion information. Transmitting information to the computer or portable terminal using the communication means; and (C) the tilt angle, height, and three-dimensional motion information of the electronic pen relative to the measured writing surface. And a method for measuring coordinates of an electronic pen data input device for a computer, comprising the step of extracting the coordinates of an electronic pen tip by conversion at a central processing unit of a terminal for a computer.
[0023]
In the present invention, the optical three-dimensional measuring apparatus includes a light emitting unit that emits a beam to form a spot on the writing surface, and a sensing unit that detects the beam spot formed on the writing surface. ) Measuring the tilt angle formed by the electronic pen and the writing surface and the height relative to the writing surface include projecting the emitted beam onto the writing surface to form a beam spot, and reflecting the beam spot. Preferably, the method includes the steps of focusing the beam and detecting the focused beam through a position detector.
[0024]
In the present invention, the step (C) includes a step of removing a gravitational component from the acceleration signal, a step of obtaining a moving speed of the electronic pen by first integrating the acceleration signal from which the gravitational component has been removed, and the electronic pen tip. After calculating the speed of the electronic pen, a step of correcting the accumulated error using the vertical speed with respect to the writing surface, a second-order integration of the movement speed of the electronic pen corrected for the movement accumulated error, and a displacement movement amount of the electronic pen And a step of correcting the accumulated error of the displacement movement amount of the electronic pen using the height with respect to the writing surface to determine the coordinates of the electronic pen tip.
[0025]
In the present invention, the communication means is preferably based on an RF communication method.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic view showing the structure of an electronic pen according to the present invention. As shown in FIG. 1, the electronic pen according to the present invention includes a three-axis acceleration sensor 4 for measuring the amount of movement caused by three-dimensional movement of the pen and an optical three-dimensional measurement for measuring the tilt angle and height of the pen. The apparatus 6-A is provided. Further, a central processing unit (CPU) 5 for receiving an acceleration signal by the triaxial acceleration sensor 4 is provided, and the speed is obtained by integrating such an acceleration signal, and the position movement amount is obtained by secondary integration. The optical three-dimensional measuring apparatus 6-A includes a light emitting unit 7 that generates a beam and a light receiving unit 8 that senses the light. In the present invention, the light emitting unit 7 uses a beam to obtain five or more beam spots 13. Is projected onto the writing surface 12 to obtain information on the tilt angle and height of the electronic pen. That is, as shown in FIG. 1, when a beam is projected onto the writing surface 12 in order to obtain the spot 13 in the original ring shape, the shape and size of the ellipse connected by the angle and height of the pen with respect to the writing surface 12 are reduced. Since it changes, the coordinate value of this spot 13 is measured to measure the tilt angle and height of the pen. It is desirable to have an optical signal processing device 6 and a CPU 5 for accepting and processing information about the tilt angle, height and movement amount of the pen as described above. However, the electronic pen according to the present invention includes the CPU 5 therein, but the information obtained by the three-axis acceleration sensor 4 and the optical three-dimensional measuring device 6-A is processed by a computer or a personal portable terminal. The CPU 5 becomes unnecessary. That is, the central processing unit is selective.
[0027]
Then, it is desirable to include a battery 3 for easily using the electronic pen for a predetermined time or more and a storage device 2 for storing information related to the movement of the pen as described above. In addition, a transmission device 1 for transmitting information about the electronic pen to a computer or a personal portable terminal is required. The electronic pen according to the present invention can be wired or wireless in data transmission. In the case of wireless, it is desirable to include an RF communication device. Usually, the writing operation with a pen is constituted by a continuous operation of pen-down and pen-up, and therefore, in order to obtain such operation information, a stress sensor 9 for determining the presence or absence of contact with the writing surface 12 can be included. In addition, since it is necessary to directly record on paper or the like, an ink storage unit 10 may be further included inside the pen.
[0028]
FIG. 2 is a view showing an embodiment of an optical pen three-dimensional measuring apparatus 6-A according to the present invention. As described above, the optical three-dimensional measuring device 6-A is for measuring the height and the tilt angle of the electronic pen with respect to the writing surface 12, and can have various structures. It is as follows. The embodiment shown in FIG. 2 shows a structure having a deviation between the center axis of the pen and the optical path projected and incident by the three-dimensional measuring apparatus 6-A.
[0029]
First, if the structure is examined, the light source 21 that emits the beam and the first lens 22 that collimates the spreading beam, the grating 23 having a certain structure, and the beam 25 emitted from the light source 21 are directed again toward the writing surface 12. A second lens 24 that projects in parallel, a camera lens 27 that collects a part of the beam 26 scattered by the writing surface 12, a position detector 28 that receives the beam condensed by the camera lens 27, and the position detector The signal processing unit senses the position using 28 signals and the arithmetic unit for calculating the height and the inclination angle with respect to the writing surface 12.
[0030]
The principle from the emission of the beam to the output of information in the optical three-dimensional measurement apparatus 6-A will be described in detail as follows. First, the light source 21 emits a beam 25 such as visible light or infrared light. In this case, the light source 21 is not limited as long as it is used as a normal light source such as a laser diode or an LED (light emitting diode). The beam emitted from the light source 21 becomes, for example, a cylindrical beam parallel by the first lens 22, and is separated into five or more beams on a circumference having a certain radius by the structure of the grating 23. The beam separated from the grating 23 is projected in the direction of the writing surface 12 through the second lens 24 for a precise parallel beam. The beam projected on the writing surface 12 forms a spot 13 in a fan-like ellipse shape by the projection angle. Here, when the writing surface 12 is a scattering surface such as wood or paper, the beam spreads at various angles, and a part of the beam is condensed on the camera lens 27 and received by the position detector 28. The information on the beam thus obtained, that is, the position of the beam spot 13 is obtained by the signal processing unit, and the height and the inclination angle with respect to the electronic pen writing surface 12 are output from the coordinates of each of the five points through the calculator. Both the position detector 28 and the signal processing unit can be configured as a single position detector. Here, it is desirable that the controller has a function of controlling on / off so that the power can be cut off when the light source 21 is not operated in order to reduce power consumption.
[0031]
FIG. 3 is a view showing another embodiment of the optical pen three-dimensional measuring apparatus according to the present invention. The optical three-dimensional measuring apparatus shown in FIG. 3 is characterized in that the center axis of the beam with respect to the writing surface is made to coincide with the center axis of the electronic pen, unlike the case of FIG. The spot scanning and reflection axis is the same as the center axis of the electronic pen.
[0032]
4A to 4F are diagrams illustrating the principle of changing the shape of a beam spot according to a change in the tilt angle and the axial direction of the electronic pen in the electronic pen optical three-dimensional measuring apparatus according to the present invention. Here, the plane on which the beam is projected is shown as an XY axis, and an axis perpendicular to the projection plane is defined as Z. The pattern of the beam connected to the writing surface is changed by changing the inclination angle variables θ1, θ2, and θ3 in the three directions. θ1 means the angle between the axis Zs in the normal direction with respect to the writing surface 12 and the central axis of the electronic pen, and θ2 is the rotated angle when the writing surface Xs-Ys and the central axis of the electronic pen are projected onto the writing surface. And θ3 means a rotation angle with respect to the center axis of the electronic pen itself. Further, δZa indicates the distance between the electronic pen tip and the writing surface. Here, the beam pattern is elliptical, and the major axis and minor axis of the ellipse and the tilt angle of the ellipse change as the tilt angle with respect to the writing surface 12 changes. Further, the size of the ellipse changes due to the pen movement in the height direction with respect to the writing surface, but when the electronic pen is close to the writing surface, the size of the entire ellipse is enlarged, and when the electronic pen is moved away, the size of the ellipse tends to be reduced. Therefore, if the beam pattern on the writing surface is read and analyzed, the tilt angle and height of the electronic pen with respect to the writing surface can be obtained.
[0033]
FIG. 4B shows the change of the major axis and shortening of the ellipse due to the change of θ1, and shows the case where θ1 is smaller than 0, the same case and the larger case from the left side form, respectively. FIG. 4C is a diagram showing changes in the major axis, minor axis, and inclination angle of the ellipse due to the change of θ2, and shows the same case and the same case when θ2 is smaller than 0 as in FIG. 4B. FIG. 4D shows the change of the spot on the circumference due to the change of θ3, where θ3 indicates the rotation angle of the central axis of the electronic pen, and therefore the positions of the five spots change according to the change of θ3. I showed it briefly. In this way, the position of the spot changes, but the shape of the ellipse does not change. However, since the elliptical image measured by the position detector 28 appears in a shape in which the image plane is rotated by θ3, the rotation angle can be measured. FIG. 4E shows a drawing form according to the change of δZa. As described above, this indicates a tendency that the entire ellipse is enlarged when the electronic pen is close to the writing surface and is reduced when the electronic pen is moved away.
[0034]
FIG. 4F shows the geometric relationship between the position detector image plane Q and the spot connected to the writing plane. Here, the coordinates Xc, Yc, and Zc are the coordinate system of the camera lens. The focal point of the position detector is defined as fc, the beam radius is defined as r, and the angle between the position detector lens axis and the light source axis is defined as Φ. Then, variables to be measured by the optical three-dimensional measuring apparatus are tilt angles θ1 and θ2 and a rotation angle θ3 of the writing surface with respect to the beam axis, and beam center coordinates Px and Pz connected to the writing surface in the camera lens coordinate system.
[0035]
If defined by an elliptic equation formed by five or more beam spots connected to the image plane Q, the elliptic equation can be expressed as follows.
[Expression 1]

ω ₁ , Ω ₂ , Ω _Three , Ω _Four , Ω _Five Is a function of the focal length fc of the lens, the radius r of the projected beam, the angle Φ between the camera lens axis and the light source axis, the vertical distance Pz of the electronic pen relative to the writing surface, and the tilt angles θ1 and θ2 of the electronic pen. Since there are five unknowns in the elliptic equation on the XY plane in Equation 1, the coordinates of the video points with respect to a minimum of 5 points are necessary. Therefore, it is desirable that the optical pen three-dimensional measuring apparatus according to the present invention is configured so that the beam emitted from the light source forms five or more spots on the image plane. This will be described in more detail with reference to Equation 2 below.
[Expression 2]

[0036]
If the elliptic equation of the image plane is calculated using the coordinates of the five spots, ω ₁ , Ω ₂ , Ω _Three , Ω _Four , Ω _Five Here, the focal length fc of the lens, the radius r of the projected beam, and the angle Φ formed by the camera lens axis and the light source are known when the electronic pen according to the present invention is manufactured. θ1 and θ2 to ω ₁ , Ω ₂ Can be calculated primarily from ω _Three , Ω _Four , Ω _Five Px and Pz can be determined. On the other hand, the rotation angle θ3 of the beam is obtained by calculating the angle at which the spot is rotated in the image as in the method presented in FIG. 4D. At this time, it is desirable to determine the rotation angle θ3 after converting the elliptic equation on the image plane into a circle equation. Since the geometrical transformation relationship between the beam axis and the camera axis is calculated through Equation 2, the virtual lens connected to the camera image plane can be obtained by matching the beam axis of the light source through movement and rotation of the camera lens central axis. The image for the circle can be calculated, and the angle of rotation of the spot at the center of the circle is calculated to determine the rotation angle θ3.
[0037]
The relationship between the parameters of the elliptic equation and the writing surface is described in a well-known reference (D. Wei, “The use of tap light for object recognitions”: Robot vision, IFS Ltd. p143-153 and “Planar Object Recognition”). A similar technology is introduced in "Development of a cylindrical laser beam projection type visual information processing system": Kim Zonghyun, Master's thesis, Department of Mechanical Engineering, Korea Institute of Science and Technology, 1989).
[0038]
FIG. 5 is a diagram showing coordinate systems in the three-axis acceleration sensor 4, the optical three-dimensional measuring device 6-A, and the electronic pen tip 11 used in the present invention. First, the coordinate system of the electronic pen tip is defined as Os, the coordinate system of the triaxial acceleration sensor 4 is defined as Oa, and the coordinate system of the optical three-dimensional measuring device 6-A is defined as Oc. Since the three coordinate systems are different due to the structure of the electronic pen, the inclination angle and height information of the electronic pen obtained by the optical three-dimensional measuring device 6-A are the inclination angle and height obtained by the electronic pen tip 11. There is a difference with information. Particularly, in the embodiment of the optical three-dimensional measuring apparatus 6-A shown in FIG. In order to correct this, it is desirable to calculate the vector E in advance as shown in FIG. Further, if the vector D is obtained from the difference between the inclination angle and the inclination angular velocity obtained in the Oc coordinate system and the information obtained in the Oa coordinate system of the triaxial acceleration sensor 4, a geometric transformation relationship between them can be obtained. The speed and the amount of position movement obtained in the coordinate system Oa of the triaxial acceleration sensor 4 are eventually converted into the coordinate system Os of the electronic pen tip, and in this case, the conversion relationship between Oa and Os can be represented by a vector L. It is a variable that can be determined in the design process of the electronic pen according to the present invention.
[0039]
FIG. 6 shows the tilt angle and height measurement variables with respect to the writing surface of the electronic pen necessary for describing the movement of the electronic pen according to the present invention, the velocity, angular velocity, and the velocity of the electronic pen tip 11 in the triaxial acceleration sensor 4 coordinate system Oa. It shows the velocity of the pen tip in the Os coordinate system and the normal vector n of the writing surface.
[0040]
FIG. 7 shows a basic structure of a sensory net for sensor fusion, which is an information processing process of the electronic pen according to the present invention. First, the speed and position of the electronic pen are determined by FTM1 (feature transformation module) using the signal output from the three-axis acceleration sensor 4, and then the signal output from the optical three-dimensional measuring apparatus 6-A is used in FTM2 An inclination angle, speed, and height with respect to the writing surface 12 of the electronic pen are obtained. In the next stage, the information received from the 3-axis acceleration sensor 4 and the optical three-dimensional measuring device 6-A by CSM1 (constant satifaction module) and CSM2 is mutually fused by using the mathematical limiting condition formula given by the following formula 2. As a result, data with reduced errors is fed back to the FTM 1 and new velocity and acceleration signals can be obtained. Formula 2 shows the limiting condition formulas for CSM1 (position) and CSM2 (speed), respectively. The basic principle of the sensor fusion technique is described in a well-known reference (Sukhan Lee, “Sensor fusion and planning with prescription-action network”, 1996, International conference on Multisense intensifier and Surgeon intension.)
[Equation 3]

Here, the restriction condition formula (1) of CSM1 is the restriction condition for the height δZs of the writing surface when the position components Xa, Ya, Za obtained inside the electronic pen are converted into the coordinate system Xs, Ys, Zs of the electronic pen tip 11. An expression is shown. The positions Xs, Ys, and Zs are obtained by integrating the acceleration signal in the electronic pen to obtain the velocity and then integrating the acceleration signal again to indicate the position. Here, α, β, γ, and λ are constants obtained from the length to the tip of the electronic pen and the tilt angle with respect to the writing surface of the electronic pen. Here, since the amount of position movement inside the electronic pen according to the limiting conditional expression can affect the height of the electronic pen tip 11, the height δZs of the electronic pen tip 11 is satisfied by a linear combination of component errors of each signal. In this way, the error accumulated in the position signals Xs, Ys, Zs of each sensor can be reduced.
[0041]
On the other hand, the CSM 2 represents the velocity component Va obtained by single integration of the acceleration signal inside the electronic pen, the angular velocity Ω of the electronic pen, and the length L to the tip of the electronic pen as a vector. The vertical velocity Vs / n is calculated from the linear velocity Vs at the pen tip and the plane normal vector n. This is because the velocity components Vax, Vay, and Vaz obtained inside the electronic pen satisfy the limiting condition formula for the writing surface, and the relationship of Vs / n = 0 when the electronic pen is in contact with the writing surface. It means to become. Further, even when the electronic pen is not in contact with the writing surface, the linear combination of the respective speed components must satisfy the limiting conditional expression, so that the cumulative error with respect to the speed can be reduced. Through the sensor fusion of the feedback system according to the present invention having the above-described structure, an increase in accumulated error can be prevented, and the amount of information can be maintained within a certain error range.
[0042]
FIG. 8 is a flowchart regarding data processing in the three-axis acceleration sensor 4 of the electronic pen and the optical three-dimensional measuring apparatus 6-A according to the present invention. First, if the ellipsoidal information of the five beam spots 13 obtained from the beam scattered on the writing surface 12 is used by the optical three-dimensional measuring device 6-A, the height of the electronic pen relative to the writing surface 12 and the position detector 28 will be described. Find the tilt angle. The process of obtaining such data is calculated by obtaining an elliptic equation using the coordinates of five or more beam spots 13 as described in FIG. If information on each inclination angle and height is obtained, an inclination angular velocity and a vertical velocity, which are differential values thereof, can be obtained from initial values.
[0043]
Then, the information signal regarding the acceleration of the electronic pen is read by the triaxial acceleration sensor 4, and at this time, the information signal output from the triaxial acceleration sensor 4 has a lot of noise, so low-pass filtering is performed. In general, since a static gravity component is always included in an acceleration signal, it is necessary to remove the gravity component from the acceleration signal in order to extract a motion signal by a pure writing operation. Since it is difficult to obtain the magnitude of each signal with respect to gravity, it is necessary to remove the gravity component with an acceleration value that changes according to the change in the tilt angle of the electronic pen using the gravity value obtained in the initial stationary state in advance. . Therefore, an acceleration signal by pure electronic pen movement is obtained. Next, such an acceleration signal can obtain information on the moving speed of the electronic pen through a first-order integration. However, since an accumulated error due to integration occurs due to noise in the information signal, Equation (3), which is a conditional expression for the speed, is applied using the speed obtained at the tip of the electronic pen in order to correct this. In order to obtain the speed at the electronic pen tip 11, it is necessary to consider the rotational angular speed of the electronic pen and the geometric variables of the electronic pen. Thus, a corrected speed value in which noise is reduced in the speed signal is obtained. This is continuously updated to a new speed value as shown in FIG.
[0044]
Next, second-order integration is performed at the moving speed obtained by the first-order integration to obtain the displacement movement amount of the electronic pen. The accumulated position error corresponding to this is calculated by using (1) of the equation 3 to obtain a newly corrected position signal as shown in FIG. The accumulated error that can be caused by double integration with the acceleration signal through the above steps is corrected step by step using each of the limiting condition equations of Equation 2 to finally move the electronic pen movement amount Xs, Ys, Zs. Is required. By using such movement amount data of the electronic pen, position data of the electronic pen according to the present invention can be obtained.
[0045]
FIG. 8 shows an embodiment in which the central processing unit 5 calculates the tilt angle, tilt angular velocity, height and vertical velocity of the electronic pen from the three-axis acceleration sensor 4 and the optical three-dimensional measuring device 6-A. As described above, such data processing is calculated in a state where the three-axis acceleration sensor 4, the optical three-dimensional measuring device 6-A, and the central processing unit 5 are provided inside the electronic pen according to the present invention, and the result value is calculated by the computer. Alternatively, it can be transmitted to a personal portable telephone terminal by wire or wireless, and only the measured amount can be transmitted and calculated by a computer or a central processing unit of the personal portable terminal.
[0046]
【The invention's effect】
According to the present invention, by integration of acceleration due to gravitational acceleration and noise of information signal of recorded information by operation of the wired / wireless electronic pen in a state where the writing surface is in contact with or disconnected from a computer or personal portable terminal. There is an advantage that the pure position coordinates of the electronic pen tip can be easily obtained by minimizing the accumulated error.
[Brief description of the drawings]
FIG. 1 is a schematic view of an electronic pen data input device for a computer according to the present invention.
FIG. 2 is a view illustrating an optical pen three-dimensional measuring apparatus according to an embodiment of the present invention.
FIG. 3 is a view showing another embodiment of the optical pen three-dimensional measuring apparatus of the electronic pen according to the present invention;
FIG. 4A is a diagram illustrating a principle of changing the shape of a beam spot according to a change in tilt angle and axial direction of an electronic pen in an optical pen three-dimensional measuring apparatus according to the present invention.
FIG. 4B is a view similar to FIG. 4A.
FIG. 4C is a view similar to FIG. 4A.
FIG. 4D is a view similar to FIG. 4A.
FIG. 4E is a view similar to FIG. 4A.
FIG. 4F is a view similar to FIG. 4A.
FIG. 5 is a diagram showing coordinate systems in a three-axis acceleration sensor, an optical three-dimensional measuring device, and an electronic pen chip used in the present invention.
FIG. 6 shows the tilt angle and height measurement variables with respect to the writing surface of the electronic pen necessary to describe the movement of the electronic pen according to the present invention, the velocity in the triaxial acceleration sensor coordinate system Oa, the angular velocity, and the Os coordinate of the electronic pen tip. It is the figure which showed the speed of the pen tip in the system, and the normal vector n of the writing surface.
FIG. 7 is a diagram illustrating a basic structure of a perceptual net for sensor fusion that is an information processing process of an electronic pen according to the present invention.
FIG. 8 is a view showing a flowchart regarding data processing in the three-axis acceleration sensor of the electronic pen and the optical three-dimensional measuring apparatus according to the present invention.
[Explanation of symbols]
1 Transmitter
2 Storage device
3 battery
4 3-axis acceleration sensor
5 Central processing unit
6 Optical signal processor
6-A Optical 3D measuring device
7 Light emitting part
8 Light receiver
9 Stress sensor
10 Ink container
11 Electronic pen tip
12 Writing surface
13 Beam spot
21 Light source
22 First lens
23 lattice
24 Second lens
25 Emission beam
26 Spot reflected light
27 Camera lens
28 Position detector
29 half mirror

Claims

In an electronic pen having a pen-shaped housing,
An optical three-dimensional measuring device for measuring the tilt angle of the center axis of the electronic pen with respect to the writing surface and the height of the electronic pen with respect to the writing surface;
A three-axis acceleration sensor for measuring the amount of movement by three-dimensional movement of the electronic pen;
An electronic pen data input device for a computer, comprising: communication means for transmitting information relating to the measured tilt angle, height, and movement amount to an external computing device.

The optical three-dimensional measuring apparatus is
A light emitting unit for emitting a beam to form a spot on a predetermined writing surface;
The electronic pen data input device for a computer according to claim 1, further comprising a sensing unit that senses a beam spot formed on the writing surface.

The light emitting unit
A light source that emits a beam;
A first lens that collimates the divergent beam produced by the light source;
A grating that separates the beam through the first lens;
The electronic pen data input device for a computer according to claim 2, further comprising: a second lens that projects a beam that has passed through the first lens toward a writing surface.

The sensing unit is
A camera lens that primarily condenses the spot beam tied to the writing surface;
The electronic pen data input device for a computer according to claim 2, further comprising a position detector that senses a beam that has passed through the camera lens.

The optical three-dimensional measuring apparatus is
A signal processing circuit for detecting the position of the beam spot using the spot beam received by the sensing unit;
5. The computer according to claim 2, further comprising an arithmetic unit that calculates a height and an inclination angle of the electronic pen with respect to the writing surface using the position of the detected beam spot. The electronic pen data input device for a computer according to one item.

5. The electronic pen data input device for a computer according to claim 2, wherein the electronic pen further includes a controller for adjusting on / off of a light source of the light emitting unit.

5. The center axis of the beam emitted from the light emitting unit of the optical three-dimensional measuring apparatus shows a predetermined deviation from the center axis of the electronic pen. 6. Electronic pen data input device for computers.

The electronic pen data input device for a computer according to claim 1, further comprising storage means for storing the information calculated by the external arithmetic device.

The electronic pen data input device for a computer according to claim 1, wherein the communication means is an RF communication device.

The electronic pen data input device for a computer according to claim 1, wherein the electronic pen further includes a battery for driving for a predetermined time.

The electronic pen further includes a central processing unit for calculating the position of the electronic pen tip using data measured by the three-axis acceleration sensor and the optical three-dimensional measuring device. The electronic pen data input device for computer as described.

The electronic pen data input device for a computer according to claim 1, further comprising a stress sensor connected to the electronic pen chip for detecting presence or absence of contact with the writing surface of the electronic pen.

3. The computer according to claim 1, further comprising an ink storage unit connected to the electronic pen chip for ejecting ink when the electronic pen is in contact with a writing surface for writing. 4. Electronic pen data input device.

An electronic pen having a pen-shaped housing;
An optical three-dimensional measuring device for measuring the tilt angle of the center axis of the electronic pen with respect to the writing surface and the height of the electronic pen with respect to the writing surface;
A three-axis acceleration sensor for measuring the amount of movement by three-dimensional movement of the electronic pen;
A central processing unit for calculating the position coordinates of the electronic pen tip using data measured by the three-axis acceleration sensor and the optical three-dimensional measuring device;
In the coordinate measurement method for an electronic pen data input device for a computer, including communication means for transmitting the calculated position coordinates of the electronic pen tip to an external computer or a personal portable terminal,
(A) Measuring an inclination angle formed by the electronic pen and a writing surface by the optical three-dimensional measuring device and a height with respect to the writing surface, and measuring three-dimensional motion information of the electronic pen by the three-axis acceleration sensor. When,
(B) extracting the coordinates of the electronic pen tip by converting the tilt angle, height, and three-dimensional motion information of the electronic pen relative to the measured writing surface with a central processing unit of a computer or a portable terminal;
(C) transmitting the extracted coordinates of the electronic pen tip to an external computer or a portable terminal using the communication means, and a coordinate measuring method for an electronic pen data input device for a computer.

The optical three-dimensional measuring apparatus is
A light emitting unit that emits a beam for forming a spot on the writing surface;
A sensing unit for sensing a beam spot formed on the writing surface,
The step of measuring the tilt angle formed by the electronic pen and the writing surface in step (A) and the height relative to the writing surface,
Emitting a beam from the light emitting portion;
Projecting the emitted beam onto a writing surface to form five or more beam spots;
Condensing the reflected beam of the beam spot;
15. The computer electronic pen according to claim 14, further comprising a step of detecting information about an inclination angle and a height formed on a writing surface of the electronic pen using the focused beam through a position detector. Coordinate measurement method for data input device.

Detecting the tilt angle and height comprises:
Obtaining the tilt angle of the electronic pen and the height relative to the writing surface by means of an elliptic equation using information on the collected five or more beam spots;
The coordinate measurement of the electronic pen data input device for a computer according to claim 15, further comprising differentiating each of the obtained inclination angle and height to obtain an inclination angular velocity and a vertical velocity from initial values. Method.

In step (B),
Removing the gravitational component from the acceleration signal;
Obtaining a moving speed of the electronic pen by first integrating the acceleration signal from which the gravity component has been removed;
After determining the speed of the electronic pen tip, correcting the accumulated error using the vertical speed with respect to the writing surface;
Obtaining a displacement movement amount of the electronic pen by second-order integration of the movement speed of the electronic pen corrected for motion accumulated error;
17. The electronic pen data for a computer according to claim 14, further comprising: correcting an accumulated error of the displacement movement amount of the electronic pen to obtain coordinates of the electronic pen tip. Coordinate measurement method for input device.

The method of measuring a coordinate of an electronic pen data input device for a computer according to claim 17, further comprising a step of performing low-pass filtering for removing noise on an acceleration signal output from the three-axis acceleration sensor.

15. The coordinate measuring method for an electronic pen data input device for a computer according to claim 14, wherein the communication means in the step (C) is based on an RF communication method.

An electronic pen having a pen-shaped housing;
An optical three-dimensional measuring device for measuring an inclination angle of the central axis of the electronic pen with respect to the writing surface and a height of the electronic pen chip with respect to the writing surface;
A three-axis acceleration sensor for measuring the amount of movement by three-dimensional movement of the electronic pen;
In a method of operating an electronic pen data input device for a computer, including communication means for transmitting information about the measured tilt angle, height, and movement amount to a computer or a portable terminal,
(A) Measuring an inclination angle formed by the electronic pen and a writing surface by the optical three-dimensional measuring device and a height with respect to the writing surface, and measuring three-dimensional motion information of the electronic pen by the three-axis acceleration sensor. When,
(B) transmitting information on the measured tilt angle, height, and three-dimensional motion information to a computer or a portable terminal using the communication means;
(C) converting the tilt angle, height, and three-dimensional motion information of the electronic pen relative to the measured writing surface with a central processing unit of a computer or a portable terminal to extract the coordinates of the electronic pen tip; A coordinate measuring method for an electronic pen data input device for a computer, comprising:

The optical three-dimensional measuring apparatus is
A light emitting unit that emits a beam to form a spot on the writing surface;
A sensing unit for sensing a beam spot formed on the writing surface,
The step of measuring the tilt angle formed by the electronic pen and the writing surface in step (A) and the height relative to the writing surface,
Projecting the emitted beam onto a writing surface to form a beam spot;
Condensing the reflected beam of the beam spot;
21. The method for measuring coordinates of an electronic pen data input device for a computer according to claim 20, further comprising: detecting the condensed beam through a position detector.

In step (C),
Removing the gravitational component from the acceleration signal;
Obtaining a moving speed of the electronic pen by first integrating the acceleration signal from which the gravity component has been removed;
After determining the speed of the electronic pen tip, correcting the accumulated error using the vertical speed with respect to the writing surface;
Obtaining a displacement movement amount of the electronic pen by second-order integration of the movement speed of the electronic pen corrected for motion accumulated error;
23. The computer according to claim 20, further comprising: correcting the accumulated error of the displacement movement amount of the electronic pen using a height with respect to a writing surface to obtain coordinates of the electronic pen tip. Coordinate measuring method of electronic pen data input device.

23. The method for measuring coordinates of an electronic pen data input device for a computer according to claim 22, further comprising performing low-pass filtering for removing noise on an acceleration signal output from the three-axis acceleration sensor.

21. The coordinate measuring method of the electronic pen data input device for a computer according to claim 20, wherein the communication means in the step (B) is based on an RF communication method.